Zettelkasten is best for what I broadly define as “Research.” The research doesn’t have to be scientific research—it can be any question without a well-known answer. “How to cure cancer?” “How to stop global warming?” “How do I become a better manager?” “How should I live my life?”—these all are great questions to research.
Google (Oxford Languages) gives the following definition of research:
the systematic investigation into and study of materials and sources in order to establish facts and reach new conclusions.
Zettelkasten principles force you to dissect your resources to “atoms”—ideas and data points—the smallest unit of mental work. Once you accumulate enough of these, you try to make sense of them and build a structure from the bottom up. Basically, you consolidate ideas and data and build a mental model of your area of research.
Zettelkasten is bad for pre-packaged learning—Zettelkasten is often picked as a learning tool but I find it ill-suited for the task.